1. Field of the Invention
The present invention relates to a roll photo film and a take-up spool combined therewith. More particularly, the present invention relates to a roll photo film and a take-up spool combined therewith, with an improvement in which a leader of the roll photo film can be easily inserted into and secured to the take-up spool.
2. Description Related to the Prior Art
There are plural known types of a roll photo film, including the 120 and 220 types. The roll photo film consists of a roll of a paper-fitted photo film. The paper-fitted photo film includes a photo filmstrip and light-shielding paper fitted thereon. The paper-fitted photo film is wound about a spool core of a supply spool in a rolled form. A leader of the light-shielding paper is bent in a position of approximately two (2) centimeters, and retained on the roll with an adhesive tape. In the 120 type of the roll photo film, the light-shielding paper is backing paper with a length greater than the photo filmstrip and is fitted on the whole of the back surface of the photo filmstrip. One end of the photo filmstrip is connected with the light-shielding paper by adhesive tape. In the 220 type of the roll photo film, the light-shielding paper is two sheets which are a leader sheet and a trailer sheet, which are connected respectively with a leading end and a trailing end. The photo filmstrip is longer than that of the 120 type, so as to increase the number of available frames to be exposed.
The supply spool has a structure standardized by ISO 732-1982, ANSI PHI 21-1980, JIS K7512-1985 and so forth. The supply spool has a pair of flanges formed on its ends for regulating respective edges of the light-shielding paper. A slit is formed in the spool core to extend in an axial direction.
To use the roll photo film, at first an empty used supply spool derived from the roll photo film used previously is set in a camera in a photo film take-up chamber, by way of a take-up spool. The leader of the light-shielding paper of the new roll photo film to be used is inserted in the slit of the take-up spool. A user's finger must manually hold the leader before the take-up spool makes at least one rotation, for the purpose of avoiding slipping the leader out of the slit. It is laborious for unfamiliar users to load a camera with the roll photo film manually.
EP-A 0 763 768 (corresponding to the commonly assigned U.S. patent application Ser. No. 08/712,387 now U.S. Pat. No. 5,845,869 and Japanese Patent Application No. 7-236993) discloses a combination of a retainer hole in the leader of the light-shielding paper and a retainer claw in the center of a wall of the slit of the spool. A pair of press ribs or ridges are formed on a remaining wall of the slit to push the light-shielding paper toward the retainer claw. The retainer claw is constituted by an erect plate and lateral claws. The erect plate is disposed on the wall. The lateral claws extend from the erect plate in the axial direction of the spool. The retainer hole has such a diameter as to receive the lateral claws at the same time. When the leader of the light-shielding paper is inserted in the slit of the take-up spool, the retainer hole of the light-shielding paper is engaged with the retainer claw of the take-up spool to retain the light-shielding paper on the take-up spool. It is possible to facilitate manual loading of the roll photo film into the camera, as there is no difficulty of manually holding the light-shielding paper with fingers.
There is a photo film holder in which a plurality of roll photo films are set before being used. Unexposed ones among the roll photo films in the holder are removed from it after taking exposures to the initial roll photo films. They are rewound in their originally wound forms of rolls, and tightly fastened with rubber bands thereabout before preservation. However the take-up spool of the above document is so constructed that it is not easy to separate the leader of the light-shielding paper from it once the leader is secured thereto. If the leader is forcibly removed, the retainer hole in it is partially damaged or broken. The leader cannot be retained to the take-up spool again when the roll photo film being still unexposed is used for next exposures.
In a photo laboratory, it is frequently necessary to separate the leader of the light-shielding paper from the take-up spool. It is not easy in the roll photo film of the above document to separate the leader from the take-up spool. The leader must be torn manually by an operator, fatiguing his hand excessively. Or the operation of tearing is not very efficient. The retainer hole could be enlarged to facilitate separation of the leader from the take-up spool. However this would cause unreliable retention of the leader to the take-up spool.
The take-up spool having the retainer claw has the appearance or contour identical with the take-up spool without a retainer claw. Should a user mistake a take-up spool without a retainer claw for one having the retainer claw, there occurs an error in winding the leader of the light-shielding paper about the take-up spool, because an end of the leader is not secured to, but has slipped out of, the take-up spool when the take-up spool is rotated only with the leader inserted in its slit.